Combustion of activated aluminum

Combustion of activated aluminum was studied by four different methods: microscopic imaging of the preignition process, digital imaging of the combustion process at pressures up to 64 bar in air, nitrogen, and carbon dioxide, TGA, and DSC. Activation by three fundamentally different methods was found effective in enhancing both the ignitability and the burn rate. The complex fluoride coating prevented agglomeration completely in all stages of combustion, while the nickel and cobalt coatings promoted agglomeration of aluminum oxide at combustion, but prevented the agglomeration of the aluminum metal before combustion. Nickel coating catalyzed aluminum nitride formation, accelerating burn rate more than other coatings in air and in nitrogen, while complex fluoride coating was most effective in carbon dioxide. Carbon coagulation in carbon dioxide quenched burning in many cases at higher pressures than 8 bar. The complex fluoride activation accelerated combustion in CO2 extremely effectively, but did not prevent carbon shell formation and subsequent quenching at high pressures. Ni coating negated the effects of carbon coagulation in CO2, but enhanced the burn rate only slightly. Co coating reduced the carbon shell formation, but did not accelerate combustion in CO2. Only the Ni coating applied in large amounts promoted combustion in nitrogen.